The procedure in the past for measuring the alignment of an input axis of a gyro has been to position shims or gauge blocks under one side or edge of the gyro instrument case and determine if the output approaches null as the instrument is rotated about a vertical axis. Since the previous method of determining input axis misalignment is a "cut & try" method, the rate table on which the gyro is mounted must be stopped many times in order to add or subtract shims or gauge blocks to null the gyro output. The previous approach is only valid for low drift rate gyros, since the time required to determine the alignment would allow the alignment data to become contaminated with gyro drift error. Therefore, it can be seen that a fixture or device is needed with which misalignment of a gyro axis can be measured automatically without having to stop the rate table or without having to add or subtract shims or gauge blocks in a trial and error approach. Rate tables are used to evaluate the performance of rate gyros. The rate table is standard test equipment for all inertial facilities. It consists of a round cylindrical platform (table top) that is rotated about a vertical axis. The speed of the table is precisely controlled by a servo motor (In this application, however, it is not necessary that the speed of the table be precisely known). The operator can control the speed of the table by making manual adjustments with external control knobs.
Therefore, it is an object of this invention to provide a dynamic alignment fixture with feedback control on which a rate gyro can be mounted and a fixture which can be mounted on a rate table for adjustment of the rate gyro relative to the rate table until the gyro output is nulled.
Another object of this invention is to automate the alignment process by providing feedback control which utilizes the output of the gyro as an error signal to drive a nulling jack-screw assembly.
Still another object of this invention is to provide a dynamic alignment fixture with feedback control that will instantaneously seek a null position while the rate table is rotating and without the use of manually operated fixture position drive motors.
Other objects and advantages of this invention will be obvious to those skilled in this art.